I've just discovered The Daily Shoot (http://dailyshoot.com). Every day, a new photo assignment is posted, and people from all over submit photographs. Today's assignment was "Think of a subject that starts with either the letter "D" or "S". Find it, and make a photo! ".
I found a conch shell, and made some macro photographs of it. This is the one I choose to submit.
I'm going to try this for a while, and see how it goes. I looks like a good way to be thinking about photography on a daily basis, even if I don't get the time to make a photograph.